Carbon material, method for producing carbon material, catalyst, dispersion liquid, electrode, battery, and electrolysis device

Abstract

A carbon material containing a fired product of a mixture containing a first compound and a second compound, the first compound being a phthalocyanine compound having bromine as a substituent, and the second compound being a compound containing at least one metal element selected from the group consisting of Fe, Co, Ni, Cu, Al, and Zn.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a carbon material, a method for manufacturing a carbon material, a catalyst, a dispersion liquid, an electrode, a battery, and an electrolytic device. BACKGROUND

[0002] Carbon materials are used for a wide range of applications due to characteristics such as high electrical conductivity, high thermal conductivity, low thermal expansion, light weight, heat resistance, and the like. In recent years, nitrogen-containing carbon materials are being studied for use as positive electrode catalysts (oxygen reduction catalysts) for fuel cells and / or air cells (see Patent Literature 1). In addition, nitrogen-containing carbon materials sometimes have carbon dioxide reduction activity and / or nitrogen reduction activity, and are also attracting attention as cathode catalysts (carbon dioxide reduction catalysts or nitrogen reduction catalysts) in electrolytic devices (see Non-Patent Literature 1 and Non-Patent Literature 2).

[0003] Prior Art Documents

[0004] Patent Literature

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2012-101155

[0006] Patent Literature 2: International Publication No. 2021 / 220495

[0007] Non-Patent Literature

[0008] Non-Patent Literature 1: Angew. Chem. Int. Ed., 2015, 54, 10758-10762

[0009] Non-Patent Literature 2: Nature Communications, 2019, 10, 341-348 SUMMARY

[0010] Problems to be Solved by the Invention

[0011] An object of one aspect of the present disclosure is to provide a novel carbon material that can be used for an oxygen reduction catalyst. In addition, an object of another aspect of the present disclosure is to provide a carbon material that exhibits excellent oxygen reduction activity.

[0012] Means of Solving the Problems

[0013] Several aspects of the present disclosure provide the following [1] to

[17] . [1]

[0015] A carbon material containing a sintered product of a mixture containing a first compound and a second compound,

[0016] The first compound is a phthalocyanine compound having bromine as a substituent,

[0017] The second compound is a compound containing at least one metal element selected from the group consisting of Fe, Co, Ni, Cu, Al, and Zn. [2]

[0019] The carbon material according to [1], wherein the phthalocyanine compound contains Fe, Co, or Zn as a central metal. [3]

[0021] The carbon material according to [1], wherein the phthalocyanine compound contains Zn as a central metal. [4]

[0023] The carbon material according to any one of [1] to [3], wherein the average number of bromine atoms of the phthalocyanine compound is 4 or more. [5]

[0025] The carbon material according to any one of [1] to [4], wherein the phthalocyanine compound is in a powder form,

[0026] The average particle diameter of the powder composed of the phthalocyanine compound is 300 nm or less. [6]

[0028] The carbon material according to any one of [1] to [5], wherein the second compound is a phthalocyanine compound or a porphyrin compound that does not have bromine as a substituent. [7]

[0030] The carbon material according to any one of [1] to [6], wherein the second compound is a compound containing Fe. [8]

[0032] The carbon material according to any one of [1] to [7], wherein the mass ratio of the content of the first compound to the content of the second compound in the mixture is 0.1 to 2000. [9]

[0034] A method for producing a carbon material according to any one of [1] to [8],

[0035] which includes a step of firing a raw material containing the first compound and the second compound.

[10]

[0037] A catalyst for a reduction reaction of oxygen, the catalyst containing a carbon material according to any one of [1] to [8].

[11]

[0039] A dispersion liquid containing the carbon material described in any one of [1] to [8] and a dispersion medium of the carbon material.

[12]

[0041] The dispersion liquid described in

[11] , which contains a high-molecular electrolyte.

[13]

[0043] The dispersion liquid described in

[11] or

[12] for use in formation of an electrode catalyst layer.

[14]

[0045] An electrode provided with an electrode catalyst layer containing the carbon material described in any one of [1] to [8].

[15]

[0047] The electrode described in

[14] , wherein the electrode catalyst layer contains a high-molecular electrolyte.

[16]

[0049] A battery provided with the electrode described in

[14] or

[15] .

[17]

[0051] An electrolytic device provided with the electrode described in

[14] or

[15] .

[0052] Effects of the Invention

[0053] According to one aspect of the present disclosure, it is possible to provide a novel carbon material that can be used for an oxygen reduction catalyst. DETAILED DESCRIPTION

[0054] In the present specification, a numerical range indicated using "~" represents a range including the numerical values recited before and after "~" as the minimum value and the maximum value, respectively. In addition, except for the case where it is specifically indicated, the units of the numerical values recited before and after "~" are the same. In the numerical range recited in stages in the present specification, the upper limit value or the lower limit value of a certain stage numerical range can be replaced with the upper limit value or the lower limit value of the numerical range of another stage. In addition, in the numerical range recited in the present specification, the upper limit value or the lower limit value of the numerical range can be replaced with the value shown in the examples (experimental examples). In addition, the upper limit value and the lower limit value recited separately can be arbitrarily combined.

[0055] Hereinafter, a preferred embodiment of the present disclosure will be described. However, the present disclosure is not limited by any of the following examples.

[0056] <Carbon Material>

[0057] One embodiment of the present disclosure is a carbon material containing a calcination product of a mixture containing a first compound and a second compound, the first compound being a phthalocyanine compound having bromine (Br) as a substituent (hereinafter, also referred to as "brominated phthalocyanine compound"), and the second compound being a compound containing at least one metal element selected from the group consisting of Fe, Co, Ni, Cu, Al, and Zn. Note that the second compound is a compound different from the first compound, for example, a compound not containing bromine (Br).

[0058] The carbon material described above exhibits excellent oxygen reduction activity because it contains the calcination product of the mixture described above. Therefore, the carbon material described above can be used as a catalyst for a reduction reaction of oxygen (oxygen reduction catalyst), for example, a catalyst for a positive electrode of a fuel cell, an air cell, or the like. In addition, the carbon material described above can also be used as a catalyst for a cathode of an oxygen electrolysis device. In addition, the carbon material described above has a tendency to exhibit carbon dioxide reduction activity and nitrogen reduction activity, and thus can also be used as a catalyst for a reduction reaction of carbon dioxide (carbon dioxide reduction catalyst) and a catalyst for a reduction reaction of nitrogen (nitrogen reduction catalyst). As specific uses, a cathode catalyst for a carbon dioxide electrolysis device and a nitrogen electrolysis device can be given. The oxygen reduction activity, the carbon dioxide reduction activity, and the nitrogen reduction activity of the carbon material can be confirmed by the method described in the examples (experimental examples).

[0059] The brominated phthalocyanine compound as the first compound has, for example, a structure represented by Formula (1) or Formula (2) described below.

[0060]

[0061] X in Formula (1) and Formula (2) 1 ~ X 16 each independently represents a hydrogen atom or a halogen atom. Among them, at least one of X 1 ~ X 16 is a bromine atom.

[0062] M in Formula (2) represents a central metal. As the central metal (M), Fe, Co, Ni, Cu, Zn, or the like can be given. Note that a phthalocyanine compound having a central metal is sometimes referred to as "iron phthalocyanine" (central metal: Fe), "cobalt phthalocyanine" (central metal: Co), "copper phthalocyanine" (central metal: Cu), "zinc phthalocyanine" (central metal: Zn), or the like, using a prefix corresponding to the kind of the central metal.

[0063] The brominated phthalocyanine compound can not have the above-mentioned central metal (M), but in the case where the brominated phthalocyanine compound has the above-mentioned central metal (M), more excellent oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity are easily obtained. From the viewpoint of easily obtaining further more excellent oxygen reduction activity, the brominated phthalocyanine compound can contain Fe, Co, or Zn as the central metal (M), and from the viewpoint of easily obtaining further more excellent oxygen reduction activity, Zn can be contained.

[0064] The halogen atom can be only a bromine atom, or a combination of a bromine atom and a halogen atom other than a bromine atom (a fluorine atom, a chlorine atom, and an iodine atom). The halogen atom can contain a bromine atom and a chlorine atom.

[0065] According to a phthalocyanine compound having bromine and chlorine as substituents, and having Zn as a central metal in the brominated phthalocyanine compound (brominated chlorinated zinc phthalocyanine), further more excellent oxygen reduction activity is easily obtained.

[0066] The brominated phthalocyanine compound contained in the mixture can be one or a plurality of kinds.

[0067] The average number of bromine atoms in the brominated phthalocyanine compound, that is, the average number of bromine atoms in the brominated phthalocyanine compound (the number of bromine atoms per 1 molecule) is more than 0, and from the viewpoint of easily obtaining more excellent oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity, can be 4 or more (for example, 4 to 16), can be 5 or more, 8 or more, or 11 or more, or can be 15 or less, or 13 or less.

[0068] From the viewpoint of easily obtaining more excellent oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity, the average number of chlorine atoms in the brominated phthalocyanine compound, that is, the average number of chlorine atoms in the brominated phthalocyanine compound (the number of chlorine atoms per 1 molecule) can be more than 0 and 11 or less, can be 0.1 or more, 0.5 or more, or 1 or more, or can be 3 or less, or 2 or less.

[0069] The average number of halogen atoms in the brominated phthalocyanine compound, that is, the average total number of halogen atoms in the brominated phthalocyanine compound (the total number of halogen atoms per 1 molecule) is more than 0, and from the viewpoint of easily obtaining more excellent oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity, can be 8 to 16, can be 11 or more, or can be 15 or less, or 14 or less.

[0070] The above-mentioned number of halogen atoms can be determined, for example, by mass spectrometry using a matrix-assisted laser desorption ionization time-of-flight mass spectrometer (JMS-S3000 manufactured by JEOL Ltd., or the like). Specifically, the number of each halogen atom can be calculated in the form of a relative value per 1 central metal element, based on the mass ratio of the central metal element to each halogen atom in the brominated phthalocyanine compound.

[0071] The brominated phthalocyanine compound is, for example, in the form of a powder. The finer the powder composed of the brominated phthalocyanine compound, the finer the sintered product, and more excellent oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity are easily obtained. From such a viewpoint, the average particle diameter (average value of the length diameter of primary particles) of the powder composed of the brominated phthalocyanine compound can be 300 nm or less (for example, 10 to 300 nm), 200 nm or less (for example, 10 to 200 nm), 100 nm or less (for example, 10 to 100 nm), 70 nm or less (for example, 10 to 70 nm), 60 nm or less (for example, 10 to 60 nm), or 40 nm or less (for example, 10 to 40 nm), or can be 40 nm or more (for example, 40 to 200 nm) or 70 nm or more (for example, 70 to 200 nm). The average aspect ratio of the powder composed of the brominated phthalocyanine compound can be, for example, 1.0 to 3.0. The powder having such an average particle diameter and average aspect ratio can be produced, for example, by the method described in International Publication No. 2021 / 220495 or the like.

[0072] The second compound contains at least one metal element selected from the group consisting of Fe, Co, Ni, Cu, Al, and Zn. In the case where the second compound contains Fe, more excellent oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity are easily obtained. In the case where the first compound has a metal element (i.e., in the case where the brominated phthalocyanine compound has a central metal), the second compound can contain a metal element different from the metal element possessed by the first compound.

[0073] In the second compound, the above-described metal element can be a metal element contained as a central metal of a phthalocyanine compound or a porphyrin compound. That is, the second compound can be a phthalocyanine compound not having bromine as a substituent, or can be a porphyrin compound not having bromine as a substituent. In the case where the second compound is a phthalocyanine compound or a porphyrin compound not having bromine as a substituent, more excellent oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity are easily obtained. The above-described phthalocyanine compound and the above-described porphyrin compound can have a halogen element (fluorine, chlorine, or iodine) other than bromine as a substituent.

[0074] The second compound can be a metal salt containing the above-described metal element. As the metal salt, there can be mentioned a sulfate, a nitrate, a carbonate, a phosphate, a chromate, a metalloporphyrin complex, a metallophthalocyanine complex, an alkali metal salt, an alkaline earth metal salt, an earth metal salt, a transition metal salt, an ammonium salt, an acid salt, an oxoacid salt, and the like.

[0075] As specific examples of the second compound, metal phthalocyanines such as iron phthalocyanine, cobalt phthalocyanine, nickel phthalocyanine, copper phthalocyanine, aluminum chloride phthalocyanine, and chloro-substituted compounds in which a part of hydrogen atoms of these metal phthalocyanines are substituted with chlorine atoms (the compound in which M is Fe, Co, Ni, Cu, Al, or Zn, and X 1 ~ X 16 in the above formula (2) is a chlorine atom); tetraphenylporphyrin iron, tris(dibenzoylmethyl) iron, iron sulfate (e.g., ferrous sulfate heptahydrate), iron chloride, and ferrous chloride (e.g., ferric chloride hexahydrate, ferrous chloride tetrahydrate), and the like.

[0076] The second compound is, for example, in the form of a powder. The finer the powder composed of the second compound, the finer the sintered product, and the more excellent the oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity are likely to be. From this viewpoint, the average particle diameter (average value of the length diameter of primary particles) of the powder composed of the second compound can be 5000 nm or less (e.g., 10 to 5000 nm), 500 nm or less, or 200 nm or less, or 30 nm or more or 50 nm or more.

[0077] The second compound contained in the mixture can be one or a plurality of kinds.

[0078] From the viewpoint of easily obtaining more excellent oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity, the mixing ratio of the first compound to the second compound, that is, the mass ratio (C1 / C2) of the content C1 of the first compound to the content C2 of the second compound in the mixture can be 0.1 to 2000, 0.2 or more, 0.2 or more, 0.5 or more, 1 or more, 2 or more, or 10 or more, or 1000 or less, 500 or less, 100 or less, 50 or less, 10 or less, 2 or less, 1 or less, or 0.5 or less.

[0079] The mixture can contain only the first compound and the second compound, or can further contain a component other than the first compound and the second compound (other component). From the viewpoint of easily obtaining a carbon material having more excellent oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity, the total content of the first compound and the second compound in the mixture can be 50% by mass or more, or 80% by mass or more, or 90% by mass or more, based on the total mass of the mixture. The total content of the first compound and the second compound in the mixture can be 100% by mass, or 99% by mass or less, or 95% by mass or less, based on the total mass of the mixture.

[0080] As the other component, for example, an organic compound not containing a metal element can be exemplified. As such an organic compound, for example, phenol formaldehyde resin, polyfurfuryl alcohol, furan, furan resin, phenol formaldehyde resin, epoxy resin, polyvinylidene chloride, polythiophene, polysulfone, polyvinyl alcohol, polyvinyl butyral, polyester, polylactic acid, polyether, polyether ether ketone, cellulose, carboxymethyl cellulose, lignin, pitch, polycarbazole, polyacrylic acid, polyacrylate, polymethacrylate, and polymethyl methacrylate, and the like can be exemplified.

[0081] As the other component, graphite, activated carbon, amorphous carbon, carbon black, coal, charcoal, coke, carbon nanotube, fullerene, graphene, and the like carbon material can also be used.

[0082] The carbon material can contain only the above-mentioned sintered product, or can contain a component other than the above-mentioned sintered product. From the viewpoint of easily obtaining more excellent oxygen reduction activity, the content of the above-mentioned sintered product in the carbon material can be 50% by mass or more, or 80% by mass or more, or 90% by mass or more, based on the total mass of the carbon material. The content of the above-mentioned sintered product in the carbon material can be 100% by mass, or 99% by mass or less, or 95% by mass or less, based on the total mass of the carbon material.

[0083] The carbon material can have a shape corresponding to the shape of the sintered product. The shape of the carbon material is not particularly limited, and can be, for example, a powder shape. The median particle diameter of the carbon material can be, for example, 0.01 to 50 μm, or 0.01 to 10 μm. The median particle diameter of the carbon material is the D50 particle diameter measured by a laser diffraction type particle size distribution measuring device equipped with an air flow type dry disperser.

[0084] The average particle diameter of the carbon material can be, for example, 0.01 to 1 μm, or 0.35 μm or less, or 0.1 μm or less, or 0.05 μm or more. Among them, when the average particle diameter of the carbon material is 0.01 to 0.35 μm, there is a tendency to easily obtain more excellent oxygen reduction activity. Note that the average particle diameter is the average particle diameter of primary particles (average primary particle diameter), and can be calculated from the average of 40 primary particles constituting the aggregate on a two-dimensional image by taking a photograph using a microscope after ultrasonic dispersion of the sample in cyclohexane.

[0085] The carbon material can have fine pores of a size corresponding to the elements other than carbon (nitrogen (N), bromine (Br), chlorine (Cl), metal elements (M), and the like) contained in the first compound and the second compound. That is, the carbon material can be a porous carbon material (for example, a powder-shaped porous carbon material).

[0086] The specific surface area (BET specific surface area) of the carbon material can be, for example, 100 m 2 / g or 300 m 2 / g or 300 m 2 / g or 300 m The specific surface area (BET specific surface area) of the carbon material can be 2000 m 2 / g or 1000 m 2 / g or 1000 m 2 / g or 1000 m From these viewpoints, the specific surface area (BET specific surface area) of the carbon material can be, for example, 100 to 2000 m 2

[0087] The carbon material described above is a material mainly containing carbon (C), but can contain elements other than carbon (nitrogen (N), bromine (Br), chlorine (Cl), a metal element (M), and the like) contained in the first compound and the second compound.

[0088] The content of carbon (C) in the carbon material can be, for example, 60% by mass or more, or 70% by mass or more or 80% by mass or more. Note that the content of carbon (C) in the carbon material is the content based on the total mass of the carbon material, and can be measured by CHN elemental analysis using a combustion method.

[0089] The content of nitrogen (N) in the carbon material can be, for example, an amount in which the number of nitrogen atoms is 0.300 or less with respect to the number of carbon atoms 1 in the carbon material, or an amount in which the number of nitrogen atoms is 0.220 or less or 0.140 or less. The content of nitrogen (N) in the carbon material can be 0 mass ppm, or an amount in which the number of nitrogen atoms is 0.005 or more, 0.010 or more, or 0.050 or more with respect to the number of carbon atoms 1 in the carbon material. Note that the number of carbon atoms and the number of nitrogen atoms in the carbon material can be measured by X-ray photoelectron spectroscopy (XPS).

[0090] The content of bromine (Br) in the carbon material can be, for example, 100000 mass ppm or less, or 50000 mass ppm or less or 20000 mass ppm or less. The content of bromine (Br) in the carbon material can be 0 mass ppm, or 50 mass ppm or more, 500 mass ppm or more, or 2000 mass ppm or more. Note that the content of bromine in the carbon material is the content based on the total mass of the carbon material, and can be measured by combustion ion chromatography (CIC).

[0091] ​The content of chlorine (Cl) in the carbon material may be, for example, 30,000 mass ppm or less, 10,000 mass ppm or less, 5,000 mass ppm or less, 1,000 mass ppm or less, 500 mass ppm or less, or 100 mass ppm or less. The content of chlorine (Cl) in the carbon material may be 0 mass ppm or 10 mass ppm or more. Note that the content of chlorine (Cl) in the carbon material is the content based on the total mass of the carbon material, and can be measured by combustion ion chromatography (CIC).

[0092] The content of the metal element (M) in the carbon material may be, for example, 20 mass% or less, 5 mass% or less, or 2 mass% or less. The content of the metal element (M) in the carbon material may be 0 mass ppm or 0.005 mass% or more, 0.1 mass% or more, or 1 mass% or more. Note that the content of the metal element is the content based on the total mass of the carbon material, and can be measured by inductively coupled plasma optical emission spectrometry (ICP-OES).

[0093] <Method for manufacturing carbon material>

[0094] Another embodiment of the present disclosure is a method for manufacturing a carbon material, which includes a step of firing a raw material including a first compound and a second compound, the first compound being a phthalocyanine compound having bromine as a substituent, and the second compound being a compound including at least one metal element selected from the group consisting of Fe, Co, Ni, Cu, Al, and Zn.

[0095] According to the above method, the carbon material of the above-described embodiments can be obtained. That is, according to the above method, a novel carbon material that can be used for an oxygen reduction catalyst can be obtained.

[0096] As the raw material, the above-described mixture can be used. That is, as the first compound and the second compound, the above-described first compound and the second compound can be used, and examples thereof are the same as the above-described examples. In addition, examples of the total amount of use of the first compound and the second compound (based on the total mass of the raw material) are the same as the above-described examples of the total content of the first compound and the second compound (based on the total mass of the mixture). In addition, examples of the ratio of the amounts of use of the first compound and the second compound (mass ratio) are the same as the above-described examples of the mixing ratio of the first compound and the second compound (mass ratio). In addition, examples of other components that can be used in the raw material are the same as the above-described examples of other components that can be included in the mixture.

[0097] The sintering temperature of the raw material can be, for example, 600°C or higher, as long as the raw material is carbonized. From the viewpoint of easily obtaining a carbon material having more excellent oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity, the sintering temperature of the raw material can be 700°C or higher, or 800°C or higher, or 900°C or higher. From the viewpoint of suppressing the high crystallization of the carbon material, the sintering temperature of the raw material can be, for example, 1500°C or lower, or 1200°C or lower, or 1000°C or lower. From these viewpoints, the sintering temperature of the raw material can be, for example, 600 to 1500°C, or 700 to 1500°C.

[0098] The sintering time of the raw material can be, for example, 0.5 to 6 hours.

[0099] The atmosphere gas at the time of sintering can be an inactive gas, an oxidizing gas, a reducing gas, or a mixed gas thereof. As the inactive gas, argon, helium, nitrogen, or the like can be exemplified. As the oxidizing gas, carbon dioxide or the like can be exemplified. As the reducing gas, hydrogen, ammonia, or the like can be exemplified. From the viewpoint of the porosity of the obtained carbon material, the atmosphere gas can include at least one selected from the group consisting of nitrogen, ammonia, and carbon dioxide. For example, if the specific surface area is increased, a gas containing ammonia can be used. By mixing helium in ammonia, there is a tendency to increase the total volume of any of mesopores or micropores. The concentration of ammonia in the gas containing ammonia can be, for example, 0.1 to 50% by volume.

[0100] The sintering of the raw material can be performed by one-stage heat treatment, or can be performed by two-stage or more heat treatment. For example, heat treatment can be performed at a temperature lower than 600°C, and then heat treatment can be performed at a temperature of 600°C or higher.

[0101] In the case where two-stage or more heat treatment is performed, the second stage can be performed under an atmosphere different from that of the first stage. By being under a gas atmosphere different from that of the first stage, the specific surface area, the total volume of mesopores / micropores, and the like can be easily controlled.

[0102] In one embodiment of the present disclosure, washing of the obtained sintered product can be performed. That is, the sintered product constituting the carbon material can also be a sintered product after washing. The washing method is not particularly limited, and for example, water washing, acid washing, alkali washing, or the like can be exemplified. From the viewpoint of controlling the content of metal elements, the washing method can be acid washing. As the acid, hydrochloric acid, sulfuric acid, or the like can be exemplified.

[0103] (Catalyst)

[0104] Another embodiment of the present disclosure is a catalyst (for example, an electrode catalyst) containing the carbon material of the above-described embodiment. The catalyst of one embodiment can be an oxygen reduction catalyst, can be a carbon dioxide reduction catalyst, or can be a nitrogen reduction catalyst. The oxygen reduction catalyst can be a two-electron reduction catalyst that catalyzes a two-electron reduction reaction of oxygen, or can be a four-electron reduction catalyst that catalyzes a four-electron reduction reaction of oxygen, but there is a tendency to exhibit more excellent catalytic activity in the case of being used as a four-electron reduction catalyst. Note that the carbon material of the above-described embodiment exhibits catalytic ability as an oxygen reduction catalyst both in an acidic condition and in an alkaline condition, and thus the oxygen reduction catalyst of this embodiment can be used both in an acidic condition and in an alkaline condition.

[0105] (Dispersion)

[0106] Another embodiment of the present disclosure is a dispersion containing the carbon material of the above-described embodiment and a dispersion medium of the carbon material. The dispersion is used for formation of an electrode catalyst layer, and the like. That is, one embodiment of the dispersion is an ink composition for forming an electrode catalyst layer.

[0107] As described above, the carbon material of the above-described embodiment can function as an oxygen reduction catalyst, a carbon dioxide reduction catalyst, or a nitrogen reduction catalyst, and thus the above-described dispersion is useful for formation of an electrode catalyst layer for an oxygen reduction electrode (for example, a positive electrode catalyst layer of a fuel cell, an air cell, or the like, and a cathode catalyst layer of an oxygen electrolysis device), an electrode catalyst layer for a carbon dioxide reduction electrode (for example, a cathode catalyst layer of a carbon dioxide electrolysis device), or an electrode catalyst layer for a nitrogen reduction electrode (for example, a cathode catalyst layer of a nitrogen electrolysis device).

[0108] As the dispersion medium, a known dispersion medium used when an electrode catalyst layer of the above-described battery and / or electrolysis device is formed can be used. For example, water, a lower alcohol (methanol, ethanol, isopropanol, n-propanol, or the like), and a mixture thereof can be used. The content of the dispersion medium in the dispersion can be appropriately adjusted so that the viscosity of the dispersion becomes a viscosity suitable for a coating device. The content of the dispersion medium in the dispersion can be, for example, 60 to 99.5 mass% based on the total mass of the dispersion.

[0109] The dispersion can be composed only of the carbon material and the dispersion medium, but in addition thereto, a known material used when an electrode catalyst layer of the above-described battery and / or electrolysis device is formed can be included. The dispersion can further contain, for example, a binder of the carbon material. As the binder, a known organic high molecular compound can be used, and from the viewpoint of being able to form an ion conduction path, a polymer electrolyte can be used. As the polymer electrolyte, for example, a perfluorosulfonic acid polymer such as Nafion (registered trademark) can be given.

[0110] In the case where the dispersion liquid contains a solid component other than the carbon material (e.g., the binder described above), the content of the carbon material can be 40 to 80% by mass, based on the total amount of the solid components in the dispersion liquid. The content of the binder in the dispersion liquid can be 20 to 60% by mass, based on the total amount of the solid components in the dispersion liquid. In the case where the dispersion liquid contains a polymer electrolyte, the content of the polymer electrolyte can be 20 to 60% by mass, based on the total amount of the solid components in the dispersion liquid. Note that the total amount of the solid components refers to the total amount of the components contained in the dispersion liquid other than the dispersion medium.

[0111] The dispersion liquid can also contain a carbon material other than the carbon material of the above-described embodiment, and the content of the carbon material other than the carbon material of the above-described embodiment can be 40% by mass or less, based on the total amount of all the carbon materials.

[0112] (Electrode)

[0113] Another embodiment of the present disclosure is an electrode provided with an electrode catalyst layer containing the carbon material of the above-described embodiment. The electrode can be an oxygen reduction electrode (e.g., the positive electrode of a fuel cell or an air cell, or the cathode of an oxygen electrolysis device), a carbon dioxide reduction electrode (e.g., the cathode of a carbon dioxide electrolysis device), or a nitrogen reduction electrode (e.g., the cathode of a nitrogen electrolysis device). The constitution of the electrode other than the electrode catalyst layer can employ a constitution known in the art for oxygen reduction electrodes, carbon dioxide reduction electrodes, nitrogen reduction electrodes, and the like. The electrode of one embodiment can further be provided with a gas diffusion layer, a microporous layer, and the like, for example.

[0114] The electrode catalyst layer can be composed only of the carbon material, or can contain a component other than the carbon material depending on its use. As the component other than the carbon material, a binder such as the polymer electrolyte described above can be given, for example. The content of the carbon material, the binder, and the polymer electrolyte in the electrode catalyst layer (based on the total mass of the electrode catalyst layer) can be in the same range as the content of the carbon material, the binder, and the polymer electrolyte in the dispersion liquid of the above-described embodiment (based on the total amount of the solid components in the dispersion liquid).

[0115] The above-described electrode catalyst layer can be formed using the dispersion liquid of the above-described embodiment. For example, the above-described electrode catalyst layer can be obtained by applying the dispersion liquid to a support and drying it. The method of application is not particularly limited, and a general method such as a bar coater, a spray coater, a screen printer, or the like can be used.

[0116] The electrode described above can also be part of a membrane-electrode assembly (MEA) that constitutes a fuel cell. The MEA has, for example, a positive electrode catalyst layer and a negative electrode catalyst layer, an electrolyte membrane disposed between the positive electrode catalyst layer and the negative electrode catalyst layer, and a pair of gas diffusion layers disposed on the side opposite the electrolyte membrane side of the positive electrode catalyst layer and the negative electrode catalyst layer, respectively.

[0117] (Battery)

[0118] Another embodiment of the present disclosure is a battery that has the electrode of the above-described embodiment. The battery is, for example, a battery that has the electrode of the above-described embodiment as an oxygen reduction electrode (positive electrode), and can be a fuel cell or an air cell. As the fuel cell, there are, for example, a solid polymer fuel cell (PEFC), a phosphoric acid fuel cell (PAFC), an alkaline fuel cell (AFC), a molten carbonate fuel cell (MCFC), a solid oxide fuel cell (SOFC), a microbial fuel cell (MFC), and the like. The configuration of the battery other than the positive electrode can employ a configuration known in the art for fuel cells, air cells, and the like. The battery of one embodiment can be, for example, a fuel cell that has a membrane-electrode assembly (MEA) including the electrode described above.

[0119] (Electrolytic device)

[0120] Another embodiment of the present disclosure is an electrolytic device that has the electrode of the above-described embodiment. The electrolytic device can be an oxygen electrolytic device that has the electrode of the above-described embodiment as an oxygen reduction electrode (cathode), a carbon dioxide electrolytic device that has the electrode of the above-described embodiment as a carbon dioxide reduction electrode (cathode), or a nitrogen electrolytic device that has the electrode of the above-described embodiment as a nitrogen reduction electrode (cathode). The oxygen electrolytic device synthesizes hydrogen peroxide with the decomposition of oxygen, and can also be referred to as a hydrogen peroxide synthesizing device. The configuration of the battery other than the cathode can employ a configuration known in the art for oxygen electrolytic devices, carbon dioxide electrolytic devices, nitrogen electrolytic devices, and the like.

[0121] Examples

[0122] Hereinafter, the content of the present disclosure will be described in more detail using examples, but the present disclosure is not limited to the examples below.

[0123] <Method for measuring the number of halogens>

[0124] The number of halogens (average number of bromine and average number of chlorine) of the materials used in the examples was found by mass spectrometric analysis using JMS-S3000 manufactured by JEOL Ltd.

[0125] <Method for measuring the average particle diameter>

[0126] The average particle diameter (average primary particle diameter) of the material used in the experimental examples was calculated from the average of 40 primary particles constituting the aggregate on a two-dimensional image, after the material was ultrasonically dispersed in cyclohexane and photographed using a microscope.

[0127] <Experimental Example 1>

[0128] As the raw material 1, a raw material powder A composed of C.I. Pigment Green 58 (zinc phthalocyanine having bromine and chlorine as substituents, average number of bromine: 11 to 16, average number of chlorine: 0 to 5, average particle diameter: 10 to 60 nm, "BrCl-ZnPc (A)" in Table 1) manufactured by DIC Corporation was prepared. In addition, as the raw material 2, iron phthalocyanine ("FePc" in Table 1, manufactured by Tokyo Chemical Industry Co., Ltd., phthalocyanine iron (II), product number: P0774, average particle diameter: 110 nm, and the like) was prepared. Next, the raw material powder A (raw material 1) and the iron phthalocyanine (raw material 2) were mixed at a mass ratio of 10: 1 (raw material 1: raw material 2), whereby a raw material mixture was prepared.

[0129] The raw material mixture 1.0 g was placed in a sintering vessel (CC mark, Nikka to manufacture SSA-S 5B; alumina 99.6%) provided in the center of a quartz reaction tube. After the air remaining in the tube was removed by flowing nitrogen at 500 ml / min for 20 minutes, the temperature was increased to 600°C (sintering temperature) at 10°C / min under nitrogen flow (500 ml / min) in a tubular furnace, and maintained for 2 hours. Then, after cooling to room temperature under nitrogen flow, the carbon material of the sintered product of the raw material mixture was taken out.

[0130] <Experimental Examples 2 and 3>

[0131] The sintering temperature was changed from 600°C to 900°C or 1000°C, and otherwise, the carbon material was produced in the same manner as in Experimental Example 1.

[0132] <Experimental Examples 4 to 11>

[0133] The mixing ratio (mass ratio) of the raw material powder A (raw material 1) and the iron phthalocyanine (raw material 2) was changed to the ratio (raw material 1: raw material 2) shown in Table 1, and otherwise, the carbon material was produced in the same manner as in Experimental Example 2.

[0134] <Experimental Example 12>

[0135] As the raw material 2, cobalt phthalocyanine ("CoPc" in Table 2, manufactured by Tokyo Chemical Industry Co., Ltd., phthalocyanine cobalt (II), product number: P0887, average particle diameter: 200 nm) was used instead of the iron phthalocyanine, and otherwise, the carbon material was produced in the same manner as in Experimental Example 2.

[0136] <Experiment Example 13>

[0137] As the raw material 2, copper phthalocyanine ("CuPc" in Table 2, manufactured by Tokyo Chemical Industry Co., Ltd., copper (II) phthalocyanine (β-form), product number: P1006, average particle diameter: 70 nm) was used instead of iron phthalocyanine, and a carbon material was produced in the same manner as in Experiment Example 2, except for this.

[0138] <Experiment Example 14>

[0139] As the raw material 2, nickel phthalocyanine ("NiPc" in Table 2, manufactured by Sigma-Aldrich Co., Ltd., nickel (II) phthalocyanine, product number: 360635, average particle diameter: 90 nm) was used instead of iron phthalocyanine, and a carbon material was produced in the same manner as in Experiment Example 2, except for this.

[0140] <Experiment Example 15>

[0141] As the raw material 2, aluminum chloride phthalocyanine ("Al(Cl)Pc" in Table 2, manufactured by Tokyo Chemical Industry Co., Ltd., aluminum chloride phthalocyanine, product number: C1167, average particle diameter: 240 nm) was used instead of iron phthalocyanine, and a carbon material was produced in the same manner as in Experiment Example 2, except for this.

[0142] <Experiment Example 16>

[0143] As the raw material 2, iron tetraphenylporphyrin ("FeTPP" in Table 2, manufactured by Tokyo Chemical Industry Co., Ltd., iron (III) tetraphenylporphyrin chloride, product number: I0937, average particle diameter: 180 nm) was used instead of iron phthalocyanine, and a carbon material was produced in the same manner as in Experiment Example 2, except for this.

[0144] <Experiment Example 17>

[0145] As the raw material 2, iron hexadeca-chlorophthalocyanine in which 16 hydrogen atoms are all replaced with chlorine atoms ("16Cl-FePc" in Table 2, manufactured by Cosmo Bio Co., Ltd., product number: 097, average particle diameter: 130 nm) was used instead of iron phthalocyanine, and a carbon material was produced in the same manner as in Experiment Example 2, except for this.

[0146] <Experiment Example 18>

[0147] As the raw material 2, ferrous sulfate heptahydrate ("FeSO4" in Table 2, manufactured by FUJIFILM and Otsuka Pharmaceutical Co., Ltd., average particle diameter: 430 nm) was used instead of iron phthalocyanine, and a carbon material was produced in the same manner as in Experiment Example 2, except for this.

[0148] <Experiment Example 19>

[0149] As the raw material 2, tris(dibenzoylmethyl) iron ("TDBM-Fe" in Table 2, manufactured by Tokyo Chemical Industry Co., Ltd., tris(dibenzoylmethyl) iron, product number: T1686, average particle diameter: 260 nm) was used instead of iron phthalocyanine, and otherwise, the carbon material was produced in the same manner as in Experimental Example 2.

[0150] <Experimental Example 20>

[0151] A raw material powder B composed of C.I. Pigment Green 59 (zinc phthalocyanine having bromine and chlorine as substituents, average number of bromine: 8 to 13, average number of chlorine: 0 to 5, average particle diameter: 10 to 60 nm, "BrCl-ZnPc(B)" in Table 3) manufactured by DIC Corporation was prepared. The raw material powder B was used instead of the raw material powder A as the raw material 1, and otherwise, the carbon material was produced in the same manner as in Experimental Example 2.

[0152] <Experimental Example 21>

[0153] In a 300 ml flask, 91 g of sulfuryl chloride (manufactured by FUJIFILM Wako Pure Chemical Corporation), 109 g of aluminum chloride (manufactured by Towa Chemical Co., Ltd.), 15 g of sodium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.), 30 g of copper phthalocyanine (manufactured by Tokyo Chemical Industry Co., Ltd.), and 230 g of bromine (manufactured by FUJIFILM Wako Pure Chemical Corporation) were charged, and the temperature was raised to 130°C, and maintained at 130°C for 4 hours. The reaction mixture (reaction solution) was taken out into water, and the precipitate was allowed to precipitate, and the precipitate was filtered and subjected to water washing, drying, whereby a crude pigment powder was obtained. 12 g of the crude pigment powder, 240 g of Japanese Sea Salt (manufactured by The Nippon Shokuhin Kogyo Co., Ltd.), and 35 g of diethylene glycol were charged into a double-arm kneader, and mixed at 80°C for 18 hours, and the obtained mixture was taken out into 700 g of water. After stirring for 1 hour, the mixture was filtered and subjected to hot water washing, drying, pulverization, whereby a raw material powder C (copper phthalocyanine having bromine and chlorine as substituents, average number of bromine: 11 to 16, average number of chlorine: 0 to 5, average particle diameter: 10 to 60 nm, "BrCl-CuPc" in Table 3) was obtained.

[0154] The raw material powder C was used instead of the raw material powder A as the raw material 1, and otherwise, the carbon material was produced in the same manner as in Experimental Example 2.

[0155] <Experimental Example 22>

[0156] As the raw material 2, cobalt phthalocyanine ("CoPc" in Table 3, manufactured by Tokyo Chemical Industry Co., Ltd., phthalocyanine cobalt (II), product number: P0887, same below) was used instead of iron phthalocyanine, and otherwise, the carbon material was produced in the same manner as in Experimental Example 21.

[0157] <Experimental Example 23>

[0158] After 91 g of sulfuryl chloride (manufactured by FUJIFILM Wako Pure Chemical Corporation), 109 g of aluminum chloride (manufactured by TOSOH CHEMICAL CO., LTD.), 15 g of sodium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.), 30 g of iron phthalocyanine, and 230 g of bromine (manufactured by FUJIFILM Wako Pure Chemical Corporation) were put in a 300-ml flask, the temperature was raised to 130°C, and the mixture was kept at 130°C for 4 hours. The reaction mixture (reaction solution) was taken out into water, and the precipitate was allowed to settle, after which the precipitate was filtered and washed with water and dried, thus obtaining a crude pigment powder. After 12 g of the crude pigment powder, 240 g of Japanese sea salt (manufactured by Nippon Suisan Kaisha, Ltd.), and 35 g of diethylene glycol were put in a double-arm kneader, the mixture was kneaded at 80°C for 18 hours, and the obtained mixture was taken out into 700 g of water. After stirring for 1 hour, the mixture was filtered, washed with hot water, dried, and pulverized, thus obtaining a raw material powder D (iron phthalocyanine having bromine and chlorine as substituents, average number of bromine: 11 to 16, average number of chlorine: 0 to 5, average particle diameter: 10 to 60 nm, “BrCl-FePc” in Table 3).

[0159] A carbon material was produced in the same manner as in Experimental Example 2, except that the raw material powder D was used instead of the raw material powder A as the raw material 1.

[0160] <Experimental Example 24>

[0161] After 91 g of sulfuryl chloride (manufactured by FUJIFILM Wako Pure Chemical Corporation), 109 g of aluminum chloride (manufactured by TOSOH CHEMICAL CO., LTD.), 15 g of sodium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.), 30 g of iron phthalocyanine, and 230 g of bromine (manufactured by FUJIFILM Wako Pure Chemical Corporation) were put in a 300-ml flask, the temperature was raised to 130°C, and the mixture was kept at 130°C for 4 hours. The reaction mixture (reaction solution) was taken out into water, and the precipitate was allowed to settle, after which the precipitate was filtered and washed with water and dried, thus obtaining a crude pigment powder. After 12 g of the crude pigment powder, 240 g of Japanese sea salt (manufactured by Nippon Suisan Kaisha, Ltd.), and 35 g of diethylene glycol were put in a double-arm kneader, the mixture was kneaded at 80°C for 18 hours, and the obtained mixture was taken out into 700 g of water. After stirring for 1 hour, the mixture was filtered, washed with hot water, dried, and pulverized, thus obtaining a raw material powder D (iron phthalocyanine having bromine and chlorine as substituents, average number of bromine: 11 to 16, average number of chlorine: 0 to 5, average particle diameter: 10 to 60 nm, “BrCl-FePc” in Table 3).

[0162] A carbon material was produced in the same manner as in Experimental Example 2, except that the raw material powder E was used instead of the raw material powder A as the raw material 1.

[0163] <Experimental Example 24>

[0164] In a 150 mL tube, 5 g of the raw material powder A and 100 g of propylene glycol monomethyl ether acetate were added, and ultrasonic treatment was performed for 8 hours at 31 kHz using a Bando Electronic bench-top ultrasonic cleaner W-113MKII. By filtration, water washing, drying, mortar crushing, the raw material powder F (zinc phtalocyanine having bromine and chlorine as substituents, average number of bromine: 11 to 16, average number of chlorine: 0 to 5, average particle diameter: 210 nm, "BrCl-ZnPc (F)" in Table 3) was obtained.

[0165] Using the raw material powder F instead of the raw material powder A as the raw material 1, a carbon material was produced in the same manner as in Experimental Example 2, except for this.

[0166] <Experimental Example 26>

[0167] In a 150 mL tube, 5 g of the raw material powder A and 100 g of cyclohexane were added, and ultrasonic treatment was performed for 8 hours at 31 kHz using a Bando Electronic bench-top ultrasonic cleaner W-113MKII. By filtration, water washing, drying, mortar crushing, the raw material powder G (zinc phtalocyanine having bromine and chlorine as substituents, average number of bromine: 11 to 16, average number of chlorine: 0 to 5, average particle diameter: 70 nm, "BrCl-ZnPc (G)" in Table 3) was obtained.

[0168] Using the raw material powder G instead of the raw material powder A as the raw material 1, a carbon material was produced in the same manner as in Experimental Example 2, except for this.

[0169] <Experimental Example 27>

[0170] In a double-arm kneader, 12 g of the raw material powder A, 240 g of Japanese sea salt (Kabushiki Kaisha Nippon Suisan Seiyu) and 35 g of diethylene glycol were mixed at 80°C for 18 hours. After the mixing, the obtained mixture was taken out into 700 g of water. After stirring for 1 hour, the mixture was filtered, and subjected to hot water washing, drying, and crushing, whereby the raw material powder H (zinc phtalocyanine having bromine and chlorine as substituents, average number of bromine: 11 to 16, average number of chlorine: 0 to 5, average particle diameter: 40 nm, "BrCl-ZnPc (H)" in Table 3) was obtained.

[0171] Using the raw material powder H instead of the raw material powder A as the raw material 1, a carbon material was produced in the same manner as in Experimental Example 2, except for this.

[0172] <Experimental Example 28>

[0173] Using zinc phtalocyanine ("ZnPc" in Table 3, manufactured by DIC Corporation, same hereinafter) instead of the raw material mixture, a carbon material was produced in the same manner as in Experimental Example 2, except for this.

[0174] <Experimental Example 29>

[0175] A carbon material was produced in the same manner as in Experimental Example 2, except that iron phthalocyanine was used instead of the raw material mixture.

[0176] <Experimental Example 30>

[0177] A carbon material was produced in the same manner as in Experimental Example 2, except that zinc phthalocyanine was used instead of the raw material powder A.

[0178] <Experimental Example 31>

[0179] A carbon material was produced in the same manner as in Experimental Example 2, except that a mixed gas of ammonia and helium (ammonia concentration: 10 vol%) was used instead of nitrogen as the flow gas.

[0180] <Experimental Example 32>

[0181] A carbon material was produced in the same manner as in Experimental Example 2, except that 0.5 g of the carbon material obtained in Experimental Example 2 and 50 ml of 1 mol / L hydrochloric acid were put in a 110-ml tube-type bottle, and stirring was performed at 70°C for 1 hour, followed by filtration and water washing. The same operation was further repeated twice, and the obtained residue was dried in an oven at 90°C for one night, thereby producing a carbon material.

[0182] <Experimental Example 33>

[0183] A carbon material was produced in the same manner as in Experimental Example 20, except that the raw material powder B (raw material 1) and iron phthalocyanine (raw material 2) were mixed at a mass ratio of 500: 1 (raw material 1: raw material 2). 0.5 g of the obtained carbon material and 50 ml of 1 mol / L hydrochloric acid were put in a 110-ml tube-type bottle, and stirring was performed at 70°C for 1 hour, followed by filtration and water washing. The same operation was further repeated twice, and the obtained residue was dried in an oven at 90°C for one night, thereby producing a carbon material.

[0184] <Analysis>

[0185] The BET specific surface area of the carbon materials of Experimental Examples 1 to 33 was measured by the nitrogen adsorption method. The measurement was performed using a full-automatic specific surface area measuring device Macsorb HM model-1208 (manufactured by Mountech Corporation), based on the "determination method of gas adsorption amount by single point method" prescribed in Appendix 2 of Japanese Industrial Standard JIS Z 8830-1990. The results are shown in Tables 1 to 3.

[0186] <Evaluation>

[0187] (Evaluation of oxygen reduction activity)

[0188] [Acidic condition]

[0189] The oxygen reduction activity of the carbon material of Experimental Examples 1 to 33 under acidic conditions was evaluated by the following method. In addition, as a reference example, the oxygen reduction activity of a platinum-supported carbon (trade name: TEC10E10E, manufactured by Tanaka Kikinzoku Kogyo K.K.) that has been used as a catalyst for an oxygen reduction electrode of a fuel cell was also evaluated.

[0190] First, 4.1 mg of the carbon material or platinum-supported carbon, 1680 μL of IPA (isopropyl alcohol), 420 μL of ultrapure water, and 30 μL of 5% Nafion (Sigma Aldrich; product number 510211) were measured into a tube-type bottle, and mixed by irradiating ultrasonic waves for 5 minutes, thereby obtaining a dispersion liquid. Four μL of the dispersion liquid was dropped on the disc portion of a platinum ring GC disc electrode (RRDE) (BAS Inc.; product number 012613; outer diameter of ring portion: 7.0 mm; inner diameter of ring portion: 5.0 mm; outer diameter of disc portion: 4.0 mm), and left to stand for about 10 minutes to dry. This was performed twice in total, and a total of 8 μL of the dispersion liquid was applied, thereby obtaining a measurement catalyst electrode (disc electrode area: 0.126 cm 2 , catalyst loading: 123 μg / cm 2 ).

[0191] Next, the oxygen reduction activity of the measurement catalyst electrode was evaluated by a three-electrode type electrochemical cell method using an Ag / AgCl electrode (BAS Inc.; product number 012167) as a reference electrode and a Pt coil electrode (BAS Inc.; product number 012961) as a counter electrode. Specifically, first, in a 0.1 M HC104 aqueous solution saturated with nitrogen gas (N2), a range of -0.1 to 0.7 V (vs. Ag / AgCl) was subjected to cyclic scanning at a scan rate of 100 mV / s, and the measurement system was stabilized. Next, in a 0.1 M HC104 aqueous solution saturated with oxygen gas (O2), linear sweep voltammetry (LSV) measurement was performed while the measurement catalyst electrode was rotated at 1600 rpm. The LSV measurement was performed by scanning a range of -0.1 to 0.7 V (vs. Ag / AgCl) at 10 mV / s from a high potential to a low potential. The potential of the ring electrode was set to a potential at which hydrogen peroxide can be sufficiently oxidized, i.e., 0.9 V (vs. Ag / AgCl).

[0192] The voltammogram obtained by measurement with the Ag / AgCl electrode was converted to an RHE reference by the following formula (a), and the disc current value I Disk , the ring current value I Ring , and the reaction start potential E onset at 0.2 V (vs. RHE) were calculated. In the following formula (a), E observed is the potential on the Ag / AgCl electrode reference, and E 0Ag / AgCl 0.195, pH 1.0.

[0193] E RHE = E 0 Ag / AgCl + 0.0590 pH + E observed … (a)

[0194] In addition, in order to confirm the proportion of the two-electron reduction reaction (reaction of generating hydrogen peroxide) in the catalyzed oxygen reduction reaction, the hydrogen peroxide generation rate (%H2O2) was calculated based on the following formula (al). Note that, for the capture rate N, the outer radius r1 of the disc portion of the disc electrode, the inner radius r2 of the ring portion of the ring electrode, and the inner radius r3 of the ring portion of the ring electrode were used, and the calculation was performed based on the following formulas (a2) to (a5).

[0195] • %H2O2 (unit: %) = 2 x I Ring / (I Disk + I Ring / N) … (al)

[0196] • N = 1 - F (a / β) + β 2 / 3 [1 - F (a)] - (1 + a + β) 2 / 3 {1 - F [(a / β) (1 + a + β)]} … (a2)

[0197] • a = (r2 / r1) 3 - 1 … (a3)

[0198] • β = (r3 / r1) 3 - (r2 / r1) 3 … (a4)

[0199] • F (θ) = [3 1 / 2 / (4π)] In [(1 + θ 1 / 3 ) / (1 + θ)] + [3 / (2π)] arctan [(2θ 1 / 3 - 1) / 3 1 / 2 ] + 1 / 4 … (a5)

[0200] In this evaluation, the potential at which the reduction current of 0.1 mA / cm 2 was passed flowed was set as the reaction starting potential, and the disc current value I Disk at 0.2 V (vs. RHE) was -1.5 mA / cm 2 In the following, in the case where the reaction starting potential was 0.5 V or more, it was judged that the carbon material had oxygen reduction activity under acidic conditions, and the disc current value I Disk at 0.2 V (vs. RHE) was -4.0 mA / cm 2Hereinafter, in the case where the reaction starting potential is 0.7 V or more, it is judged that the carbon material has excellent oxygen reduction activity under acidic conditions. In addition, among the carbon materials judged to have oxygen reduction activity, the carbon material having a hydrogen peroxide generation rate (%H2O2) of 30% or more is judged to be particularly useful as a two-electron reduction reaction catalyst, and the carbon material having a hydrogen peroxide generation rate (%H2O2) of 15% or less is judged to be particularly useful as a four-electron reduction reaction catalyst. The results are shown in Tables 1 to 3.

[0201] [Alkaline conditions]

[0202] Using 0.1 M KOH aqueous solution instead of 0.1 M HCIO4 aqueous solution, changing the range of -0.1 to 0.7 V (vs. Ag / AgCI) to the range of -0.7 to 0.1 V (vs. Ag / AgCI), and setting the potential of the ring electrode to 0.2 V (vs. Ag / AgCI), otherwise, the same as the above-described measurement method under acidic conditions, the oxygen reduction activity of the carbon materials of Experimental Examples 1 to 27 and 31 to 33 under alkaline conditions was evaluated. Among them, the value of the pH of the above-described formula (a) for converting the voltammogram to the RHE reference was 13.

[0203] In this evaluation, the potential at which the reduction current of 0.1 mA / cm 2 was passed was set to the reaction starting potential, and the disc current value I Disk at 0.4 V (vs. RHE) was -2.8 mA / cm 2 Hereinafter, in the case where the reaction starting potential is 0.6 V or more, it is judged that the carbon material has oxygen reduction activity under alkaline conditions, and the disc current value I Disk at 0.4 V (vs. RHE) is -4.0 mA / cm 2 Hereinafter, in the case where the reaction starting potential is 0.85 V or more, it is judged that the carbon material has excellent oxygen reduction activity under alkaline conditions. In addition, among the carbon materials judged to have oxygen reduction activity, the carbon material having a hydrogen peroxide generation rate (%H2O2) of 30% or more is judged to be particularly useful as a two-electron reduction reaction catalyst, and the carbon material having a hydrogen peroxide generation rate (%H2O2) of 15% or less is judged to be particularly useful as a four-electron reduction reaction catalyst. The results are shown in Tables 1 to 3.

[0204] [Table 1]

[0205]

[0206] [Table 2]

[0207]

[0208] [Table 3]

[0209]

[0210] (Evaluation of carbon dioxide reduction activity)

[0211] The carbon dioxide reduction activity of the carbon materials of Experimental Examples 1 to 33 was evaluated by the following method.

[0212] First, a catalyst electrode for measurement was prepared in the same manner as in the evaluation of oxygen reduction activity. Next, the carbon dioxide reduction activity of the catalyst electrode for measurement was evaluated by a three-electrode electrochemical cell method using an Ag / AgCl electrode (BAS Inc.; product number 012167) as a reference electrode and a Pt coil electrode (BAS Inc.; product number 012961) as a counter electrode. Specifically, first, after the measurement system was stabilized by performing cyclic voltammetry in the range of -1.8 to -0.7 V (vs. Ag / AgCl) at a scan rate of 100 mV / s in a 0.5 M KHCO3 aqueous solution saturated with argon (Ar), LSV measurement was performed while rotating the catalyst electrode for measurement at 1600 rpm, whereby a voltammogram was obtained. Next, LSV measurement was performed while rotating the catalyst electrode for measurement at 1600 rpm in a 0.5 M KHCO3 aqueous solution saturated with carbon dioxide (CO2), whereby a voltammogram was obtained. The LSV measurement was performed by scanning the range of -0.8 to -0.1 V (vs. RHE) at a rate of 5 mV / s from a high potential to a low potential. The voltammogram obtained by subtracting the voltammogram under argon saturation from the voltammogram under carbon dioxide saturation was taken as the voltammogram of the carbon dioxide reduction reaction, and the current value at -0.7 V (vs. RHE) was calculated by converting the obtained voltammogram to the RHE reference using the above-described formula (a). Here, the value of pH used in the above-described formula (a) for converting the voltammogram to the RHE reference was 8.36. The greater the current value in the negative direction in the voltammogram of the carbon dioxide reduction reaction, the higher the carbon dioxide reduction activity.

[0213] In this evaluation, the current value at -0.7 V (vs. RHE) in the voltammogram of the carbon dioxide reduction reaction was -0.05 mA / cm 2 In the following cases, the carbon material was judged to have carbon dioxide reduction activity (Evaluation A or B), and the current value at -0.7 V (vs. RHE) in the voltammogram of the carbon dioxide reduction reaction was lower than -0.4 mA / cm 2 In the following cases, the carbon material was judged to have excellent carbon dioxide reduction activity (Evaluation A). The evaluation results are shown in Table 4. Note that the evaluation results of Experimental Examples in which the carbon material was judged not to have carbon dioxide reduction activity are denoted as C.

[0214] (Evaluation of nitrogen reduction activity)

[0215] The nitrogen reduction activity of the carbon material of Experimental Examples 1 to 33 was evaluated by the following method.

[0216] First, a catalyst electrode for measurement was prepared in the same manner as in the evaluation of the oxygen reduction activity. Next, the reference electrode used an Ag / AgCl electrode (BAS Inc.; product number 012167), the counter electrode used a Pt coil electrode (BAS Inc.; product number 012961), and the nitrogen reduction activity of the catalyst electrode for measurement was evaluated by a three-electrode electrochemical cell method. Specifically, first, after the measurement system was stabilized by performing cyclic voltammetry in the range of -1.7 to -0.5 V (vs. Ag / AgCl) at a scan rate of 100 mV / s in a 0.1 M Na2SO4 aqueous solution saturated with argon (Ar), LSV measurement was performed while rotating the catalyst electrode for measurement at 1600 rpm, whereby a voltammogram was obtained. Next, LSV measurement was performed while rotating the catalyst electrode for measurement at 1600 rpm in a 0.1 M Na2SO4 aqueous solution saturated with nitrogen (N2), whereby a voltammogram was obtained. The LSV measurement was performed by scanning the range of -0.8 to 0 V (vs. RHE) at 5 mV / s from a high potential to a low potential. The voltammogram obtained by subtracting the voltammogram under argon saturation from the voltammogram under nitrogen saturation was taken as the voltammogram of the nitrogen reduction reaction, and the current value at -0.8 V (vs. RHE) was calculated by converting the obtained voltammogram to the RHE reference using the above-described formula (a). Here, the value of pH used in the above-described formula (a) for converting the voltammogram to the RHE reference was 5.8. The greater the current value in the negative direction in the voltammogram of the nitrogen reduction reaction, the higher the nitrogen reduction activity.

[0217] In the present evaluation, the current value at -0.8 V (vs. RHE) in the voltammogram of the nitrogen reduction reaction was -0.02 mA / cm 2 In the following cases, the carbon material was judged to have nitrogen reduction activity (Evaluation A or B), and the current value at -0.8 V (vs. RHE) in the voltammogram of the nitrogen reduction reaction was lower than -0.3 mA / cm 2 In the following cases, the carbon material was judged to have excellent nitrogen reduction activity (Evaluation A). The results are shown in Table 4. Note that the evaluation results of Experimental Examples in which the carbon material was judged not to have nitrogen reduction activity are denoted as C.

[0218] [Table 4]

[0219] CO2 reduction activity [N2 reduction activity] Experimental Example 1 B C Experimental Example 2 A A Experimental Example 3 A A Experimental Example 4 C C Experimental Example 5 A C Experimental Example 6 A A Experimental Example 7 A A Experimental Example 8 B B Experimental Example 9 B C Experimental Example 10 C C Experimental Example 11 A B Experimental Example 12 A A Experimental Example 13 A A Experimental Example 14 A A Experimental Example 15 B B Experimental Example 16 A B Experimental Example 17 B B Experimental Example 18 A C Experimental Example 19 A A Experimental Example 20 C B Experimental Example 21 A C Experimental Example 22 C C Experimental Example 23 C A Experimental Example 24 C C Experimental Example 25 A A Experimental Example 26 A A Experimental Example 27 A A Experimental Example 28 C C Experimental Example 29 C C Experimental Example 30 C C Experimental Example 31 A A Experimental Example 32 A A Experimental Example 33 C C

Claims

1. A carbon material comprising a sintered product of a mixture containing a first compound and a second compound, the first compound being a phthalocyanine compound having bromine as a substituent, the second compound being a compound containing at least one metal element selected from the group consisting of Fe, Co, Ni, Cu, Al, and Zn.

2. The carbon material of claim 1, wherein, the phthalocyanine compound contains Fe, Co, or Zn as a central metal.

3. The carbon material of claim 1, wherein, the phthalocyanine compound contains Zn as a central metal.

4. The carbon material of claim 1, wherein, the phthalocyanine compound has an average number of bromine of 4 or more.

5. The carbon material of claim 1, wherein, the phthalocyanine compound is in a powder form, a powder composed of the phthalocyanine compound has an average particle diameter of 300 nm or less.

6. The carbon material of claim 1, wherein, the second compound is a phthalocyanine compound or a porphyrin compound not having bromine as a substituent.

7. The carbon material of claim 1, wherein, the second compound is a compound containing Fe.

8. The carbon material of claim 1, wherein, a mass ratio of a content of the first compound to a content of the second compound in the mixture is 0.1 to 2000.

9. A method for producing a carbon material according to any one of claims 1 to 8, which comprises a step of sintering a raw material containing the first compound and the second compound.

10. A catalyst for a reduction reaction of oxygen, the catalyst comprising a carbon material according to any one of claims 1 to 8.

11. A dispersion liquid containing a carbon material according to any one of claims 1 to 8 and a dispersion medium of the carbon material.

12. The dispersion liquid according to claim 11, which contains a high-molecular electrolyte.

13. The dispersion liquid according to claim 11, which is used for formation of an electrode catalyst layer.

14. An electrode provided with an electrode catalyst layer containing a carbon material according to any one of claims 1 to 8.

15. The electrode of claim 14, wherein, the electrode catalyst layer contains a high-molecular electrolyte.

16. A battery provided with the electrode according to claim 14.

17. An electrolytic device provided with the electrode according to claim 14.

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